The objectives of this research are to analyze cytotoxic T lymphocyte lines (CTLL) generated in vitro against murine plasmacytoma-associated antigens. CTLL have been generated from normal lymphoid cells by multiple stimulations with plasma cell tumors. These CTLL have been propagated in IL-2 and have been cloned to produce lines which are reactive with individual antigenic determinants. The first major emphasis of these investigations has been to use these cloned lines to study the complex array of tumor-associated antigens which have been described on plasma cell tumors, particularly whether the major histocompatibility gene products play a role in the cytotoxic T-cell response to these antigens. Our results indicate that some of these cytotoxic T-cell lines are H-2 restricted, whereas others are not. A second major emphasis has been to characterize the CTL populations and cloned lines for cell surface phenotype and in vivo and in vitro activity. Cell surface analyses have been carried out by immunofluorescence, using flow cytometry analysis employing a battery of monoclonal antibodies against lymphoid differentiation antigens, including Thy-1, Lyt-1 and Lyt-2. These studies indicate that Lyt-2 expression is not essential for killing by cytotoxic T cells. In the coming year, in vivo studies will be done to analyze the activity of lines with different cell surface phenotypes and different specificities. Effort will continue to concentrate on correlating cell surface phenotypes with functional activity.